Method of constructing safety inner tubes



March 27, 1945. F. A. KRUSEMARK 2 METHOD OF couswnucwme SAFETY INNERTUBES Filed Aug. 8, 1940 6 Sheets-Sheet l v Q IINVENTOR.

.%Q12ZZ %m mw March F K S K METHOD OF CONSTRUCTING SAFETY INNER TUBESFiled Aug. 8, 1940 6 Sheets -Sheet 2 WWM March 27, 1945. F. A. KRUSEMARKMETHOD OF CONSTRUCTING SAFETY INNER TUBES Filed Aug. 8, 1940 6Sheets-"Sheet 4 INVENTOR March 27, 1945. F. A. KRUSEMARK 2,

' METHOD OF CONSTRUC'IING SAFETY INNER TUBES Filed Aug. 8, 1940 6Sheets-Sheet 5 INVENTOR.

BY M

March 27, 1945. I I F. A. KR QEMARK 2,372,382

METHOD OF CONSTRUCTING SAFETY INNER TUBES Filed Aug. 8, 1940 6Sheets-Sheet 6 INVENTOR.

Patented Mar. 27, 1945 Frederick A. Krusemark, Chicago, 11]., assignorto The Mansfield Tire and Rubber Company, Mansfield, hio,acorporation ofOhio Application August 8, 1940, Serial No. 351,826

9 Claims.

This invention has to do with the manufacture of inner tubes of theso-called multiple chamber type, such, for example, as is set forth inmy Letters Patent Number 2,307,002 granted December 29, 1942. Morespecifically, this invention provides a method of constructing safetyinner tubes, hereafter called safety tubes.

In the past, the usual methods of manufacturing safety tubes providedfor the construction and curing of the inner unit comprising generallythe inner air chamber, then removingsaid unit from the mold andcompleting the construction by adding the outer air chamber unit andthen replacing the whole arrangement in another mold I and curing itagain to complete the unit. This is an involved and expensive procedureusing considerable time with its attendant costs and delays, andrequires extra equipment.

Itis an object of the present invention to provide means of eifecting amanufacture of a. comv plete properly cured safety tube by the use of asingle cure operation, thus eliminating. where desired, the double cure.

In this connection, as indicated above, the building of the tubes now onthe market usually involves partial building before the first cure andfurther building after the first cure. It is an object of the presentinvention to disclose a method of building a safety tube which completesthe building of the tube before any curina operation takes place.Carrying this a step further, it is another object of this invention toprovide a method of manufacture in which a double cure may be used ifdesired, but which will involve no additional building operations afterthe first cure; other than placing in a second mold, inflating anadditional amount. and completing the cure.

It is a further object of the present invention to provide a method andmeans whereby the inner air chamber is temporarily blocked oif from theouter air chamber during the curing operation so that inflation of theinner air chamber for curing purposes does not pass any substantialamount of air or inflating fluid to the outer air chamber, thus causingthe outer air chamber to cure in contact with the wall structure of theinner air chamber unit and the curing heat to penetrate the materialsforming both units and cure said materials at the same time.

Y use of a bead structure which retains various parts of the safety tubestructure from moving operation performs the desired functions of a beadstructure.

- It is a further object of the present invention to provide a. methodof manufacture in which the forming operation before placing in the moldis much improved over that of other methods of manufacture and whichforming operation en ables the tube to be built flat and then properlyshaped and proportioned before placing in the mold for curing. In thisconnection, it is another object of this invention to provide a formingoperation which enables the manufacturer to expand the tube to its outerdesired circumference without distorting the base or throwing the tubeout of balance, and then forming the base structure to its inner desiredcircumference.

It is another object of the present invention to provide an arrangementwhereby the entire safety tube can be built flat; that is, fiat on thecustomary building drum.

It is another object of the present invention to disclose a method andprocedure of building an inner tube which is much less expensive than 1methods in use today, and which involve a considerable saving of time ascompared with the methods in use today for building multiple chambersafety inner tubes.

Other objects and advantages of the invention will appear as the natureof the improvements is better understood, the invention consistingsubstantially in the novel construction, combination and arrangement ofparts hereinafter fully described, illustrated in the accompanyingdrawings, and finally pointed out in the appended claims.

In the drawings Figures 1 to 8 inclusive are longitudinal sectionalviews through a building drum, such as commonly usedin the manufactureof tubes and tires, showing successive steps in the building operationand the materials as added;

Figures 9 to 12 inclusive are likewise longitudinal sectional viewsthrough a drum, showing It is another object of the present inventiontofurther successive steps in-the building operation, the drum, however.in these figures being shown in a fragmentary view;

Figures 13, 14, 15 and 16 show the use of the forming drum in themanufacture of safety inner tubes and the like, the view being across-sectional view throughthe forming drum;

Figure 17 is a vertical elevational view of the safety tube afterremoval from the forming drum and before placing in the mold for thecuring operation;

out of position during cure. and also in normal Figures 18 and 19 show across-sectional view through. a safety inner tube such as may be builtby the method disclosed herein, Figure 18 showing the tube as it iscured by a single operation and before inflation, and Figure 19 showinthe tube of Figure. 18 after inflation. Fisure 19 equally well shows acompleted tube performed by the one cure method, as it would look wheninflated or shows a tube one step further advanced than thetube ofFigure 18, when a double cure'operation is performed; 7

Figures 20, 21, 22, 23, 24 and 25 are views similar to Figures 1 to 8,but illustrate modifications of my process and method of manufacture;and the remaining figures from Figure 26 to 31, both inclusiveare'likewise cross-sectional views illustrating modifications, theshowing of the building drum, however, being fragmentary only.

Referring more in detail to the various constructions shown in thedrawings, I provide the building drum 40, which may be theconventiontions or the beads in the finished tube. Each should bepositioned with respect to the sides of al drum used today, and it ispreferably made so that it may be expanded or shrunk within limits,

as desired.

referred to as the beads 42, which are placed over said sheet 4|circumferentially. These beads 42 are preferably of material containingcords or they may be formed with wire beads. These beads perform severalvery desirable functions among which are that they hold the variousparts subjected to strain in the forming and curing operation enablingsaid parts to. retain their proper position'and result in a balancedtube after the curing operation. It is to be noted that the beads 42should be very carefully positioned on the sheet 4!, the position beingdetermined by the diameter of the building drum upon which the tube isbuilt in relation to the position the head is to assume inthe curedproduct. They must be properly placed however since they do not stretchmaterially in the curing operation, and since the other portions of thetube may stretch such as the base when it constricts inwardly,stretching in some portions and shrinking in others, and the outer airchamber structure and some of the inner air chamber structure isexpanded outwardly in the forming operation and in the curing process.These beads however since theydo not stretch materially must bepositioned so that they will be where they are of the propercircumference for the completed safety tube.

The bead performs, in both the building operaproximate position wherethe material inside or between the bead strips moves outwardly in theforming operation, and the material outside of (or later becoming thebase portion of the tube as shown in subsequent steps) start moving in-.wardly, there being little or no movement at the position where thebeads are located. Failure to properly position these beads tends tothrow a tube off balance in the finishing operation and in the finishedproduct. 7 Usually, experiment in building any. size 0 tube willindicate the exact position for the beads 42. The beads also may beusedto mark automatically the position of various steps used in theperforming operation, suchfor instance is a step subsequently describedwherea dusting or painting operation known to the trade as lubricating,is performed to prevent the walls of the inner and outer air chambersadhering in the limits of said air chamber, and thus forming said airchamber. In this connection, it may be that the operator will paint upto or just over the bead, as desired, or each side, although the beaddoes not necessarily mark the limit of the lubricating operation.

One tube built experimentally by this operation had the bead placed sothat its outer edge was approximately two inches from the edge of thesheet 4|. In connection with the above operation, it is to be noted thatin the forming and curing operation, various portions of the tube inexpanding may tend to distort by curl or turn or otherwise move, andthis head structure maintains the proper relationship of said portionswith the remainder of the safety tube structure.

In the finished product, the cordsperform the normal functions of a.cord and assist in maintaining the safety tube properly positioned inthe tire, and also they tend to prevent the inner air chamber frommoving to a position of contion and actual operation inthe tire on a'vethe more they will stretch in the forming and.

building operations, and in use. The bead 42 on each side runslongitudinally and at little or no angle to the longitudinalcircumference, and hence will have little or no stretch.

The position of each of the beads42 is determined on each size of tubeby -the diameter of thebuildingdrumandthediameterofthepositact with thecrown of the outer air chamber, restraining movement under centrifugalforce. This is very desirable for obvious reasons.

The beads may be any size desired, but a preferable sizeis aboutone-half inch in width.

The operation shown in Figure 3 comprises the placing of a second sheet43 over said first sheet 4| and beads 42. Preferably this second sheetis of a, fabric material similarto sheet 4|, and preferably also thesheet is brought just over the outer edges of the bead 42 and stitchedor otherwise fastened to the sheet 4!. The fabric mate-- pointed out,become what may be considered.

a single unit or sheet. I will refer frequently to the assembledmaterials constituting sheets 4! and 43, and beads 42 as the fabric.

As shown in Figure 4, there are two operations provided. The firstoperation consists of punching the hole in'the fabric, somewhere betweenthe limits forming the inner chamber as pointed out in later steps. Thishole may be punched by hand or by machinery, using a leather punch orany other suitable punch desired. The other step shown is the step ofplacing, over said hole, a patch of gum coated cellulose tape, commonlycalled Scotch tape" or the like 45. This Scotch tape" will generallyadhere somewhat to the area around the holeand will provide a seal oversaid hole during the forming operation equivalent'of the solution. Manysolutions are commonly known to the trade for this purpose,

such 'for example as soapstone and water; or

glycerine, alcohol and mica; or any of the wellknown soap solutionscombined with soapstone and mica if desired. I

The solution is preferably placed over the fabric and beads to aposition, say, for example,

a couple of inches from the edge of the material on each side.

This distance is determined by preferance as it may vary overaconsiderable It is an expedient useful in manufacturing to provide whatmay be designated as marker strips.

(not shown) for use in lubricating as above described. These markerstrips are merely circumferential strips or sheets of material, insertedover the edge of the drum and overthe fabric to the positionof the outerlimits where the solution is desired. These cover. the portions not tobe lubricated and enable a person to blow the solution on with a sprayergun or paint with a paint brush, rapidly and without danger of carryingthe solution too far or splashing where not desired. These marker stripsare removed after the lubricating operation,. and

- may be used time after time for the same purpose. I

The solution abovementioned is shown in Fig- 'ure 5 as a layer, theshowing preferably being exaggerated for that purpose as in Figure 5.The solution is designated here as solution 46, and is shown asextending from the inside of one bead to the inside of the other bead,although it may extend across the bead if desired. Preferably thesolution covers the Scotch tape, too, on the upper side as shown inFigure 5.

Referring to Figure 6, I show a further step consisting of placing asheet of material such as rubber over the arrangement of Figure 5, andpreferably bringing this sheet of material to approximately the outerlimits of the sheet 4!. This material is of such construction as rawrubber stock and is here designated as the outside wall 41 which formsthe outer wall of the outer air chamber in the finished safety tube. Theoutside wall will adhere with the fabric, particularly with the sheet4|, except where the solution 46 covers said fabric. It is merelynecessary to place said outside wall on the fabric and press it down orstitch it, or, if desired, cement it or otherwise attach, assuringadhesion where desired. y

It may'well be pointed out that fabric material has a tendency toconduct air much like a capillary attraction action; that is, it willoperate as a wick and conductair from air chamsequent steps'in theprocess of building which comprise removing the assembly built up inFigures 1 to 6 from the drum, and turning it inside out to thearrangement shown in Figure '7, here-" in called reversing, then fillingthe. hole 44 with wax such'as the wax known tothe trade as Flexo" wax,and then attaching the valve 48.

over the opening or hole t4. This valve 48 may be of any desired form,and in fact may be eliminated and merely a restricted opening 44provided in place thereof such as that obtained by using a grommet orotherwise. It is .understood, however, that while the hole 44 may besealed by means of the Scotch tape," or by means of the wax alone or anyother means, it is usually desirable to use both in the ordinaryoperation. This wax and Scotch tape. preferably maintain the seal untilat least a portion of the curing operation is completed, and untilafterall of the.

expanding operation hereinafter discussed as forming operation, has beencompleted. When the safety tube is inflated'after the curing operationor at some time during the curing operation perhaps without additionalinflation, the' Scotch tape and the wax to seal the hole 44, the Scotchtape usually pulling loose and falling harmlessly into the outer airchamber, and the wax either disintegrating or melting out from the heat.It isnot believed necessary to denote specific com-position of waxesused, although preferably a greaseless wax is used and one which willnot melt until the temperatures are considerably increased. -The heatcauses the cellulose or other material composing the Scotch tape to curland pull away from the hole, or if it fails to do that because of theadhesion of the gum, inflation after curing will blow the tape lo0se.-If necessary, the tube may be taken in the fingers and the tape pulledloose bywrinkling the tube.

Referring to Figure 8, I have provided the gum strips 49 which areplaced over the'sheet of material M in the manner shown in Figure 8.These gum strips may extend inwardly only a short waysor preferablyextend over the fabric to a positionunder the inner tube as shown inFigure 9, and when so extended have a tendency to prevent the wickaction discussed above in connection with some of the other figures.This particularly true since the hole at usually has fabric materialexposed to the air in the tube.

Referring next to Figure 9, the inner air chamber may be formed inseveral ways by a completed inner tube preferably of raw stock, such asis facturing the tube but which is preferably about that shown in Figure9 ascontacting sheet 4|.

This inner tube is designated as inner air chamber unit 50, the aircontaining portion thereof usually being referred to asinner air chamber50. The addition of the word unit describes the complete structureforming the inner air chamber, and this unit 50 is that structure in thearrangement here shown. Preferably the inner air chamber unit 50contains the inlet valve ner air chamber, and retaining the shape forcuring.

5| which usually opens into the inner air chamture touches the guides54, which is the position shown in Figure 14.

taches thereto. The solution maintains the parts from sticking. One ofthe gum strips 49 may be omitted and the otherstrip extended'out so thatin subsequent operations, to be described particularly in connectionwith Figure 11, one of the gum strips comes all of the way over theinlet valve 5| and attaches to the other edge of the face of the sheet4!, eliminating using two strips.

This is merely a variation, however, and will be The inlet valve is.then plugged by means of a'cap,"or a waxplug or rubber P1118. or anyother type or plug desired (not shown) whereby the inflating fluid isretained in the safety tube. Since the hole 44 from the inner airchamber to the outer air chamber is plugged by means ;of the Scotchtape" 45 01 the wax (above described) or both, the inflating fluid willnot flow into the outer air chamber, ,and the outer wall 41 will lieadjacent, or against, the fabric structure forming the wall between theinner and outer air chambers, and the heat used in the curing operationwill be easily transmitted between the various layers offabric andrubber comprising pointed out more in detail in connection with ,otherfigures.

' As shown in Figure 11,the edges (and so much .of the material asfollows naturally'the movement of the gum stri and fabric) are turnedinwardly and brought over the inner air chamber unit. For this purposethe gum strips may each have a half circle hole cut out to match thehole in the other and accommodate the valve 5|, or one gum strip may, asabove mentioned, have a hole therein and be slipped entirely over thevalve 5|. T176 solution l5! prevents the turned up portions fromsticking to the innerair champer unit except where desired, and when theedges have been turned over as shown in Figure 11,\the

upper portion of the gum strip is as shown in that figure and the edgeportions along the top,

'after the turning process, are still tacky.

v The base strip 52, having an opening therein to accommodate the valve51, is placed in position and scaled down on the tacky surface of thegum l strips, and if desired the outside wall 41, thus forming aprotective flap or portion over the intube units in The complete safetytube is thus built flat and is now ready for the forming operation. The

building drum 40 is collapsed if of the collapsible type, otherwise thesafety tube is just "pulled off of the building drum, and again turnedinside out, or reversed for the forming drum. The forming operationisone of the important steps as at present indicated in building thissafety tube,

for the reason that improper forming will tend to pull the units apart,will distort the tube, and

will be objectionable. I have provided a forming procedure which is verydesirable and enables the tube to be formed quickly for the mold,without injury or undesired distortion.

Preferably a forming drum is provided which is collapsible; that is,which may. have its circumference constricted. The forming drum shouldhave a hole for insertion of the inlet'valve aftertlce safety tube hasbeen reversed. Thisforming drum may be either built on a platform asshown in Figure 13, the platform being numbered I52, and having the drumwalls 53, or the platform may be eliminated, and any means of holdingthe safety tube in place on the walls 53 may be used (includingfriction).

Preferably one or'more guides 54 are provided, and are positioned toindicate the outerlimits of expansion desired in the forming operation.

The tube is-inserted on the forming drum so or concave portion on itssurface.

that the forming drum preferably provides a support for the'bead rtionof the safety tubeat least, the support generally being at the base. Airor other inflating fluid is forced into the inlet. valve until the crownportion of the tube structhe whole tube that a rapid cure of the unitsof both air chambers at the same time is accom- 'plished.

In this connection, the material forming the fabric and other units ofthe inner air chamber may be of composition that cures more rapidly thanthat of the outer air chamber, particularly the outside wall ll of theouter air chamber. By this means the inner wall between the two airchambers may be entirely cured at the same time as the outside wall 41,or prior to completion ofthe cure of the outside wall 41 as hereafterindicated, and thus be assured of proper curing.

After the step shown in Figure 14, it is'desirable to contractthe innerwall 53 of the forming drum so that the base of. the safety tube movesinwardly and is formed, the inner circumference being generallydetermined by the distance such forming drum constricts inwardly. Byforming the safety tube thus and expanding the outer portion outwardlyand constrict ing the base inwardly, the various layers of mate-Y rialdo not pull apart. The inner tube is preferably supported at all timesin the forming operation at the beads and the base, and thebeads- Imaintain the'parts in proper position if such support atthe beads ispresent. Upon contraction or constriction of the inner walls of thedrum, the heads will probably be some distance from the inner wall inthe position shown in Figure .15. The beads however still maintain theparts against rolling sideways and the inner wall of the drum providesadditional support.

As shown in Figure 16, I have provided a modifled type of forming drumwhich has a recessed When the safety tube is placed on the drum, it issupported by the vertical face portions 55, herein referred to as face55, on either side of the recessed portion. Preferably these faces 55,should be in the position to support'the beads 42, as the safety tubeupon inflation constricts radially inward from the inner edges of thefaces 55, and the concaved. surface 56 is or becomes little by little,

the support for the structure at the base and from the base to thebeads, as clearly apparent Figure 1'? shows the safety tube as itappears I when ready for insertion into the mold, for the curingoperation, it having much the appearance of an ordinary tube.

It is desirable to describe the curing operation although no moldequipment is shown,- or believed necessary in the illustrations.Preferably a mold is used which has been vented to eliminate trappedair. .This is not absolutely necessary; however, and more or lessstandard equipit is harmless. The curing operation may cause the Scotchtape 46 to pull away from the hole 44. and the wax in sald'hole 44 tomelt. If the Scotch tape does not pull away, it may be easily brokenaway after removal from the mold by distorting the safety tube aroundthe position of the Scotch tape, or .even by merely additionallyinflating the inner air chamber, thu blow ing it away. y

It is considered satisfactory to have the com-- pleted tube after curingwith the inner air chamber andouter air chamber, lying close to etherscribed, up to the limits determining the outer may be pushed into theinner air chamber where as shown in Figure 18. To eliminate possibleopening of the hole 44 and blowing away of the "Scotch tape 45,'andextension of the wall 41 to an arrangement as shown in Figure 19.This position would be determined by the capacity of the larger heateror mold, in normal procedure.

the arrangement is built up without taking off the drum until ready forforming. As' shown in Figure 20, the outer wall 41 is-placed around thedrum. This outer wall has, preferably, the permanent markers 51, whichmark the outer limits of the outer air chamber. 1 Markers 51 may be justa rubber strip or the like or may be a ledge on the outer wall 41, madewhen forming the outer wall.

The outer wall 41 is lubricated as shown at 10 in Figure 21 by one ofthe solutions above deair chamber, preferably within the limits shown-by the markers 51. The fabric sheet 4|, with the beads 42 and fabricsheet 43 are preferably assembled fiat on a table, having. the hole 44punched therein and a piece of Scotch tape" 45 placed under the hole sothat in the position shown in Figure 22 the, Scotch tape" will bebetween the fabric and the outer wall 41 and covering the hole 44. Thisassembly is then placed over the outer wall as shown in Figure 22, andjoined circumferentially in the outer edges to the outer wall 41, bystitching or the like outside" thelimits of the solution shown in Figure,1. As shown in Figure 23; I have provided the side strip 58 'whichperforms the same func-- tion as the gum strips 49 shown in Figure 8,etc. This strip 58 may be integral with the outside wall 41, and ispreferably'made by merely extending the outside wall 41 out suflicientlyto form the necessary extra portion. It is here shown as Y a 'separatestrip. It is provided with a hole or opening 59 which accommodatesthevalve stem. Obviously, two narrower strips may be provided,

. one on each side, so long as there is sumcient The safety tube maythen be given a further cure,

The'tube is then removed from the mold and placed in use.

If the additional cure just above described is not used, and the tube asshown in Figure 18 is placed in the tire, inflated and run, the outerwall 47 will gradually become more or less permanently positioned awayfrom the inner air chamber unit'at the crown, and from the standpoint ofutility there is no serious objection to curing the tube as in Figure18. If desired, the outer wall 41 may be of a somewhat heavier stock toallow for thinning by stretch upon inflation. This is a matter of themanufacturers preference, however.

Referring to the modifications, it is considered feasible, and in factit may be preferable, to'build up the units disclosed in Figures 1, 2, 3and 4, on

a table before placing on a drum. In such event the ends of the units ofsaid figures as represented by the sheets and 43' and the beads 42 maybe slightly overlapped when placing on a drum and sealed" together,assuring a good unipn. In such a building operation it would I ReferringtoFigures 20 to 25 inclusive, I show a modified process of building thesafety tube wherein it is unnecessary to reverse the assembly -in thestep shown inFigure'7. In otherwords,

material of this nature to go across and form a flap over the base ofthe tube.

Referring to Figure 24, I have shown an arstructure may then be finishedas provided in Figures 9, et seq.

Another modification consists of building up the structure as shown inFigures 1 to 8, both inclusive, and in providing an inner air chamberstructure as shown in Figure 26. This comprises a tube sheet 60 which isplaced over the valve and fabric structure taking the place of the innertube shown in Figure 9. This tube sheet 60 is more economical because aportion of the rubber forming the inner air chamber is eliminated. Thisportion which is eliminated is not absolutely necessary, as the fabricis usually rubber coated and makesa satisfactory wall regardless ofwhether rubber coated or not when used between the two air chambers.

The arrangement shown in Figure 2'7 is similar to that of Figure 26except the edges of the tube sheet are turned under making a smootherunion. In these two arrangements, the procedure subsequently followed isthe-same as is shown in Figures l0,et seq.

In Figure 28, I have shown the arrangement of Figure 7 having addedthereto on one side an extended gum strip 49, having inlet valve, and

preferably on the other side a gum strip 49. As

chamber already built up. It is desirable in the.

structure of Figures 28 and 29 that the upper surface of the fabric(except under the gum strip 49, and under the tube sheet 60', aswell asthe portion shown as the top of the tube sheet 60', which forms theinner wall of the inner air chamber unit) be'painted with solution toprevent sticking. The gum strip 49 however sticks to the tube sheet Ifdesired the gum strip 49 may be eliminated and the tube strip 60increased in size so 'that when it is brought over the fabric, etc., asshown in Figure '7 and is curled over and attached to the edge of thetube sheet 60 it completes the inner air chamber.

It is understood that a simple although probably not so desirablearrangement, may be made by merely using an outside wall 41 which is extended on one side and has a valve going through,

asvases r said valve being an inlet valve. See Figures and 31.Preferably it ispositioned in the building operation, on to the side ofjoinder with the fabric sheet, such as sheet 4|. This fabric sheet isplaced over the outside wall '41 a'fter a solution has been painted onone or the other (the outside wall or fabric sheet) at a positionbetween the two, except where they are joined along the edges of thefabric 4|. Preferably in such an arrangement the markers 51 areprovided, and Scotch 'pe is provided over the hole or grommet or valveopening of some type in the fabric 4l. This hole is numbered 44 to beconsistent with the other showing in the other figures. The outside wall41 containing the valve is then curled over and joined at the edges, asolution being inserted between the top of the fabric 4| as shown inFigure 30 and the sheet 41 where it passes over said fabric 4!. Thisforms the double air chamber I arrangement. Of course other means ofblocking the hole 44 may be employed but a feasible means is that shownby use of Scotch tape" and/orwax. The safety tubes of Figures 29 and 31are ready for the forming operations.

It is to be understood that other processes of forming may be employedthan that shown, such asvery slowly inflating the safety tube thedesired amount. The method disclosed however is very desirable, but I donot intend to limit myself thereto except that I may do so in theclaims.

The form of the invention herein shown and described presents apreferred embodiment thereof, and delineates its adaptation to practicaluse,

but it is to be understood that the present disclosure is to beconsidered from the illustrative standpoint and not as imposingrestriction or limitation on the invention.

While I have herein shown and described certain features of myinvention, still I do not wish to limit myself thereto, except as Imaydo so in the claims.

I claim: I 1. A method of forming, in the process of bull ing a safetyinner tube and the like having multiple .air chambers with at least onebase portion,

' comprising building up the units of said "safety tube, placing saidunits on a means supporting said base'of said safety tube, and expandingsaid safety tube to a predetermined outer circumference, thenconstricting the base supporting means to a predetermined innercircumference, and thereby causing said base portion of said safety tubeto constrict to a desired inner circumference.

2. A method of forming in the building operation, a safety inner tubehaving inner and outer air chambers, comprising building up the units ofthe safety tube and placing them substantially uninflated on a formingdrum whichsupports at least a portion of said safety tube whereby theunits of said safety tube are prevented from pulling apart in theforming operation, and expanding the safety tube to predetermined outerand inner dimensions, the operation being such that the base of saidsafety tube constricts inwardly for a portion of said forming operationand another portion of said safety, tube expands outwardly. 1

' 3. A method of forming in the building operation, a safety inner tubehaving inner and outer air chambers,-comprising building up the units ofthe safety tube and placing them substantially uninflated on a formingdrum which supports at least a portion of said safety tube whereby theunits of said safety tube are prevented from pulling apart in theforming operation, and expanding the safety tube to predetermined outerand constricted inner circumference dimensions.

4. The process of manufacturing a safety inner tube consisting ofplacing a sheet of rubber said fabric, lubricating said inner airchamber 4 unit a predetermined amount, bringing said side strip oversaid inner air chamber unit, and sealing'said side strip to the materialcomprising the opposite edge of said fabric and outside wall assembly,removing said safety tube assembly from said building drum, and formingand ouring said safety tube.

5. A method of building a. safety inner tube upon a building drum,comprising placing a layer of rubberized fabric on said building drumand joining the ends of said rubberized fabric together, attaching aplurality of bead strips on said rubberized fabric a predetermineddistance from each of the side edges thereof, attaching a second layerof rubberized fabric having a hole therein over said first layer ofrubberized fabric and over said head strips, with the cords of therespective layers angularly disposed with respect to one another,sealing said hole with a waxy sealing material, lubricating the uppersurface ofthe upper sheet of fabric in the area within and apredetermined distance from the respective edges, placing a strip ofrubber material comprising the outside wall over the lubricant and onthe portion not lubricated and attaching said outside wall to saidfabric where not :lubricated, reversing the structure on said drumwhereby the outside wall is next to said drum. placing a valve over saidhole and attaching said valve to said fabric, attaching a gum strip onthe edges of said fabric circumferentially of said drum, attaching aninner air chamber unit having an inlet valve and an aperture over theupper face of said fabric on said building drum, with the openingaligned with said valve attached to the fabric, preventing said innerair chamber attaching to said fabric'and gum strips egzcept in apredetermined amount by lubricating, --turning the edges 'of said fabricand gum strips up over i the inner air chamber unit, attaching a basestrip circumferentially around said structure to said gum strips therebycompleting a flap over the base of said structure, removing saidstructure from said building drum and reversing whereby the inlet valveis on the inner circumference of said fabric material over the inner an:chamber unit, and attaching across the base ofthe inner air chamberunit, circumferentially placin said structure on a'forming drum-andexpanding to a predetermined outer circumference and constricting to apredetermined inner cir-\ cumference, removing said structure from saidforming drum, and curing, and removing: said said inlet valve into theinner air chamber, said outer air chamber unit curing substantiallyagainst said inner air chamber unit, and removing said cured structurefrom the mold.

6. A method of building a safety tube and the like comprising attaching,bead means to a layerof material such as rubberized fabric, placing asecond layer of material such as rubberized fabric over said first layerabovementioned and said bead means, providing a hole through said layersof material, providing a seal means for said hole, placing an outsidewall of material such as rubber over said structure hereinbeforedescribed, and attaching said outside wall to said fabric materialabovementioned 'at predetermined places, placing an inner air chamberunit on'theeother side of said first-mentioned fabric, attaching theside edges of said outside wall to each other over the base of the innerair chamber unit, and forming and at least partially curing said unitswith the inner air chamber unit sealed off from the outer air chamberunit whereby inflating fluid in saidinner air chamber unit is restrainedfrom passing to the outer air chamber unit between said outside-wall andsaid fabric material.

'7. A method of building a safety inner tube by use ofa building drum,comprising placing material such as rubberized fabric on said buildingdrum and fastening the ends of said mate.- rial together, providing a,hole ough said fabric,-temporarily sealing said h e, lubricating theouter surface of the fabric material within a precured structure fromthe mold.

8. A process of manufacturing an inner safety tube and the likecomprising placing a. sheet of rubberized material having an inlet valvein the margin of one side thereof on a building drum, placing a sheet offabric material having an opening therethrough on said rubberizedmaterial, sealing said opening by a removable adhesive sheet of materialfolding said rubberized material over said fabric material and joiningthe edges of said rubberized material, removing said units so built upfrom the building drum and placing on a forming drum, forming said .unit

so built up by expanding the outer circumference to a predeterminedposition and constricting the inner circumference to a predeterminedposition, placing said'formed unitin a. curing means such as a mold, andcuring with the fabric determined distance from its respective edges,

attaching a sheet of rubber material comprising the outside wall on thefabric material and attaching to the portion not lubricated, reversingthe structure on said, drum whereby the outside wall is next to saiddrum, attaching material forming at least a base portionof an inner airchamber unit over the upper face of said fabricmaterialonsaidbuildingdrumturningtheedgea material against therubberized material substantially throughout the area of the fabricmaterial.

9. The process of manufacturing a safety innet tube comprising placing asheet of rubber suitable to form an outside wall on a building drum,lubricating the center area only of the sheet, leaving the marginaledges unlubricated, placing a fabric assembly having a hole therein oversaid outside wall sheet, temporarily sealing said hole by placing a waxysubstance therein,

attaching a side strip to at least one edge of said outside wall,attaching a valve over said -hole in said fabric, placing over andattaching to said fabrican inner air chamber unit, lubricatingsaid innerair chamber unit where unattached to said fabric, bringing said sidestrip over said inner air chamber unit, and sealing said side strip tothe material comprising the opposite edge of said fabric and outsidewallassembly, said material over said inner air chamber unit beingprevented from adhering thereto by said lubricant abovementioned,removing saidsafety tube assembly from said building drum, and formingand curing said safety tube.

mnnmcx A. man

